This invention concerns space-dyeing of synthetic yarns. The term "space-dyeing" refers to a dyeing process whereby dye is applied intermittently along the length of yarn such that, when the yarn is woven or knitted into a fabric, a more or less random color pattern is produced in the fabric.
In the past, there have been many attempts to provide space-dyed yarn by applying tints and dyes to one or both ends of a yarn package which, upon being woven or knitted into a fabric, yielded an intermittent color effect. These attempts to date have generally not provided dyed fabrics having commercially acceptable wet processing (wash fastness) characteristics.
U.S. Pat. No. 4,097,232 discloses a process for treating yarn packages with dyes followed by introducing heated steam for a time sufficient to cause the dyes to partially penetrate the yarn package. This process involves treating yarn in package from with one or more dyes or dye acceptance modifiers to modify or dye the yarn fibers in a reproducible manner to provide repeating contiguous sections of yarn having desired characteristics. In a preferred process, a dye acceptance modifier in the form of a resist is infused into one or both of the ends of a yarn package and a heated fluid (steam) is then introduced under pressure at a temperature and for a time sufficient to cause the resist to at least partially penetrate the package and contact individual strands of yarn or fibers, and to set the resist.
U.S. Pat. No. 3,986,235 discloses a process for producing space-dyed textile strands by a process of contacting each of the flat ends of a wound yarn package with a coloring agent, withdrawing the yarn from the yarn package, and rewinding the yarn in reverse order into a second yarn package having at least one substantially flat end, and then contacting each of the flat ends of the rewound yarn package with a color modifying agent, e.g. a dye. The colored yarn can then be withdrawn from the rewound yarn package and woven or tufted into a carpet, for example, and dyed, resulting in a carpet having random flecks of contrasting color therein.
Copending United States Patent Application Ser. No. 946,607, filed in the name of Allen A. Wiggins, Jr., discloses a process in which partially oriented synthetic yarn such as partially oriented polyester yarn is fed continuously first to and through a bath of a liquid conditioning agent such as a sublimatable dye, then to a first heated roll and then to a second heated draw roll to draw the partially oriented yarn, then to a texturizer and then to a takeup roll, all in one continuous operation, to produce a conditioned and texturized yarn product possessing about 12% to about 30% latent shrinkage. Also provided is a process for dyeing undrawn, partially drawn or fully drawn synthetic yarns using sublimatable inks. A method of space-dyeing using a gravure-type roll applicator is also disclosed therein.
The aforementioned references, either alone or in combination, do not disclose space dyeing of unoriented or partially oriented synthetic yarns, using a sublimatable ink dyeing agent, by a method of applying the sublimatable ink to at least one end of at least one yarn package and thereafter drawing and heating and texturizing the yarn to produce a space-dyed, textured yarn. Further, the references do not disclose a process for producing a highly random color pattern in a woven or knitted fabric by feeding, in a predetermined sequence, multiple ends of multicolored, space-dyed yarn packages produced by the process of this invention. Such process and the products produced thereby are the subject of the present invention.
By way of definition, the following terms are used herein. The term "undrawn yarn" is used to designate synthetic yarn having no orientation of its molecules or, at most, only a small degree of orientation, which yarn has been drawn prior to processing according to this invention to a degree considerably less than two (2) times its as-spun undrawn length.
The term "yarn package" means yarn wound upon a core by the yarn manufacturer, and rewinding upon a special dyeing package is unnecessary.
The term "sublimatable ink" as used herein refers to inks made primarily for printing applications. Insofar as is known, they consist of disperse dyes ground to a very fine particle size, and suspended in a water solution with the aid of suitable dispersing agents. They are generally intended for use where the ink is first applied to a printing paper and then transferred to a fabric being dyed by means of sublimation of the pigment and transferral to the fabric in the vapor phase. To satisfy various applications, these inks are available commercially in three general energy levels. Energy level indicates the degree of heat required to vaporize the dye-stuff so that it will transfer to the medium being printed. The lower the energy level, the easier it is to transfer the ink. However, the lower energy inks may produce printings which are deficient in light and wash fastness. The high energy inks are more difficult to transfer but generally give printed fabrics having outstanding levels of light and wash fastness.
Preferred dyes include dyes manufactured by Ault and Wiborg, Ltd., London, England, including:
Aultran* Red F02 PA1 Aultran Red F04 PA1 Aultran Blue F56 PA1 Aultran Blue F57 PA1 Aultran Yellow F23 PA1 Aultran Yellow F24 PA1 Aultran Violet F62 PA1 Aultran Black F81 FNT *"Aultran" is a trademark of Ault and Wiborg PA1 (a) applying to at least one end of at least one package of synthetic polymeric yarn a solution of a sublimatable dye pigment, PA1 (b) drying the dyed yarn package, PA1 (c) withdrawing at least one end of the yarn from at least one package and directing the yarn end to and around a first rotating predraw roller and thence to and around a second rotating, heated draw roller rotating at a faster peripheral speed than the first roller to impart draw to the yarn, PA1 (d) feeding the dyed and drawn yarn to and through a texturizer, and PA1 (e) accumulating the dyed, drawn and texturized yarn on a takeup device.
It is believed that these dye pigments are sublimatable anthroquinone, azo and methine dyestuffs.